// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Runtime.Serialization;

namespace System.Reflection.TypeLoading
{
    /// <summary>
    /// Base class for all Module objects created by a MetadataLoadContext.
    /// </summary>
    internal abstract partial class RoModule : Module
    {
        private readonly string _fullyQualifiedName;

        internal const string FullyQualifiedNameForModulesLoadedFromByteArrays = "<Unknown>";

        internal RoModule(string fullyQualifiedName)
            : base()
        {
            Debug.Assert(fullyQualifiedName != null);

            _fullyQualifiedName = fullyQualifiedName;
        }

        public sealed override string ToString() => Loader.GetDisposedString() ?? base.ToString();

        public sealed override Assembly Assembly => GetRoAssembly();
        internal abstract RoAssembly GetRoAssembly();

        internal const string UnknownStringMessageInRAF = "Returns <Unknown> for modules with no file path";

#if NET
        [RequiresAssemblyFiles(UnknownStringMessageInRAF)]
#endif
        public sealed override string FullyQualifiedName => _fullyQualifiedName;
        public abstract override int MDStreamVersion { get; }
        public abstract override int MetadataToken { get; }
        public abstract override Guid ModuleVersionId { get; }

#if NET
        [RequiresAssemblyFiles(UnknownStringMessageInRAF)]
#endif
        public sealed override string Name
        {
            get
            {
                string s = FullyQualifiedName;
                int i = s.LastIndexOf(Path.DirectorySeparatorChar);
                if (i == -1)
                    return s;

                return s.Substring(i + 1);
            }
        }

        public abstract override string ScopeName { get; }

        public sealed override IList<CustomAttributeData> GetCustomAttributesData() => CustomAttributes.ToReadOnlyCollection();
        public abstract override IEnumerable<CustomAttributeData> CustomAttributes { get; }

        public sealed override object[] GetCustomAttributes(bool inherit) => throw new InvalidOperationException(SR.Arg_ReflectionOnlyCA);
        public sealed override object[] GetCustomAttributes(Type attributeType, bool inherit) => throw new InvalidOperationException(SR.Arg_ReflectionOnlyCA);
        public sealed override bool IsDefined(Type attributeType, bool inherit) => throw new InvalidOperationException(SR.Arg_ReflectionOnlyCA);

        public abstract override FieldInfo? GetField(string name, BindingFlags bindingAttr);
        public abstract override FieldInfo[] GetFields(BindingFlags bindingFlags);
        public abstract override MethodInfo[] GetMethods(BindingFlags bindingFlags);
        protected abstract override MethodInfo? GetMethodImpl(string name, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[]? types, ParameterModifier[]? modifiers);

#if NET
        [Obsolete(Obsoletions.LegacyFormatterImplMessage, DiagnosticId = Obsoletions.LegacyFormatterImplDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]
        [EditorBrowsable(EditorBrowsableState.Never)]
#endif
        public sealed override void GetObjectData(SerializationInfo info, StreamingContext context) => throw new NotSupportedException();
        public abstract override void GetPEKind(out PortableExecutableKinds peKind, out ImageFileMachine machine);

        public abstract override Type[] GetTypes();
        internal abstract IEnumerable<RoType>? GetDefinedRoTypes();
        public abstract override bool IsResource();

        public sealed override FieldInfo ResolveField(int metadataToken, Type[]? genericTypeArguments, Type[]? genericMethodArguments) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);
        public sealed override MemberInfo ResolveMember(int metadataToken, Type[]? genericTypeArguments, Type[]? genericMethodArguments) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);
        public sealed override MethodBase ResolveMethod(int metadataToken, Type[]? genericTypeArguments, Type[]? genericMethodArguments) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);
        public sealed override byte[] ResolveSignature(int metadataToken) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);
        public sealed override string ResolveString(int metadataToken) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);
        public sealed override Type ResolveType(int metadataToken, Type[]? genericTypeArguments, Type[]? genericMethodArguments) => throw new NotSupportedException(SR.NotSupported_ResolvingTokens);

        public sealed override Type? GetType(string className, bool throwOnError, bool ignoreCase)
        {
            //
            // This looks bogus and against the intended meaning of the api but it's pretty close to the .NET Framework behavior.
            // The .NET Framework Module.GetType() will search the entire assembly when encounting a non assembly-qualified type name but
            // *only* as long as it's a generic type argument, not the top level type. If you specify the name of a type in a
            // different module as the top level type, this api returns null (even if throwOnError is specified as true!)
            //
            Type type = Assembly.GetType(className, throwOnError: throwOnError, ignoreCase: ignoreCase)!;
            if (type.Module != this)
            {
                // We should throw if throwOnError == true, but .NET Framework doesn't so we'll keep the same behavior for the few people using this.
                return null;
            }
            return type;
        }

        /// <summary>
        /// Helper routine for the more general Module.GetType() family of apis. Also used in typeRef resolution.
        ///
        /// Resolves top-level named types only. No nested types. No constructed types. The input name must not be escaped.
        ///
        /// If a type is not contained or forwarded from the module, this method returns null (does not throw.)
        /// This supports the "throwOnError: false" behavior of Module.GetType(string, bool).
        /// </summary>
        internal RoDefinitionType? GetTypeCore(ReadOnlySpan<byte> ns, ReadOnlySpan<byte> name, bool ignoreCase, out Exception? e)
        {
            if (ignoreCase)
                throw new NotSupportedException(SR.NotSupported_CaseInsensitive);

            int hashCode = GetTypeCoreCache.ComputeHashCode(name);
            if (!_getTypeCoreCache.TryGet(ns, name, hashCode, out RoDefinitionType? type))
            {
                type = GetTypeCoreNoCache(ns, name, out e) ?? new RoExceptionType(ns, name, e);
                _getTypeCoreCache.GetOrAdd(ns, name, hashCode, type); // Type objects are unified independently of this cache so no need to check if we won the race to cache this Type
            }

            if (type is RoExceptionType exceptionType)
            {
                e = exceptionType.Exception;
                return null;
            }

            e = null;
            return type;
        }
        protected abstract RoDefinitionType? GetTypeCoreNoCache(ReadOnlySpan<byte> ns, ReadOnlySpan<byte> name, out Exception? e);
        internal readonly GetTypeCoreCache _getTypeCoreCache = new GetTypeCoreCache();

        internal MetadataLoadContext Loader => GetRoAssembly().Loader;
    }
}